Compressor venting system



D86. 1964 G. -r. PRIVON ETAL 3,162,360

COMPRESSOR VENTING SYSTEM Filed May 14, 1962 2 Sheets-Sheet 1 INVENTORS'. GEORGE T. PRIVON. TADEK M. KROPIWNICKI.

ATTORNEY.

1964 ca. T. PRIVON ETAL 3,152,360

COMPRESSOR VENTING SYSTEM Filed May 14, 1962 2 Sheets-Sheet 2 IN VENTORS.

GEORGE T. PRIVO. TADEK M. KROPIWNI ATTORNEY.

United States Patent 3,1623% KIOMPliEdd-th VENTENG SYSTEM George T. Prison, Camillus, and Tadelr M. Kropiwniclri,

Syracuse, FLY. assignors to Carrier Corporation, Syraruse, N.Y., a corporation of Delaware Filed May 14, 1962, Ser. No. 1%,3tl7 2 Claims. (Cl. 23tl2ll6) The present invention relates to hermetic compressors and, more particularly, to hermetic compressors in which the crankshaft thereof is vertically disposed.

Generally, in hermetic compressors having vertically disposed crankshafts in which the motor is mounted over the compression mechanism, the bearing located between the motor and the compression mechanism handles the load of the compression mechanism and the motor. It has been found that the problem of lubricating this hearing is acute because of its remoteness from the oil sump. During shut-down of a compressor the lubrication passages above the oil sump level fill with refrigerant vapor. Upon start-up of the compressor, it is desirable to vent these lubrication passages as rapidly and effectively as possible so that the entrapped refrigerant will not starve the bearings of lubrication.

Venting of the lubrication system may be done by either venting into the compressor crankcase or into the motor chamber. Venting into the compressor crankcase eliminates the danger of lubricant entrained in the rerigerant finding its Way into the refrigeration circuit where a film of lubricant may be deposited on the heat exchange surfaces thereby reducing the capacity of the refrigeration system as a whole and reducing the supply of lubricant available for lubricating the compressor. Venting into the motor chamber removes refrigerant gas from the lubrication system and reduces the possibility of vapor lock since venting is done into a low pressure area. It is noted that the crankcase pressure is higher than the motor compartment pressure. Thus, venting into the motor compartment uses to advantage this pressure differential. Venting into the motor compartment also reduces lubricant pump noise caused by lubricant entrained refrigerant gas since refrigerant gas is removed from the lubrication system. The present invention contemplates a unique compressor crankshaft configuration especially adapted for hermetic compressors to effectively vent refrigerant gas to the motor comparement thereby insuring a continuous flow of lubricant to the bearings.

The chief objective of the present invention is to provide a hermetic compressor having a crankshaft with an improved configuration adapted to provide controlled venting of the lubrication system into the motor compartment.

Another object is to provide a compressor having a crankshaft with an internal oil passage configuration effective to remove gaseous refrigerant from the lubrication system.

A still further object is to provide a compressor having a vertically disposed crankshaft having means for directing oil from the pump to the crankshaft bearing and venting oil borne refrigerant gas into the motor comparb ment. These and other objects will become more apparent from the following description.

The present invention relates to a reciprocating compressor having a compression mechanism operatively associated with a vertically disposed crankshaft. Also connected to the crankshaft and mounted above and partitioned from the compression mechanism is a suitable driving motor. Crankshaft journaling bearing means are located between the motor and the compression mechanism. The compressor is provided with a suitable lubrication pump. An oil passage in the crankshaft communicates the oil pump with the crankshaft bearing means.

' shell in communication.

A vent passage communicates the oil passage with the area adjacent the motor. The compressor is of a type wherein the suction gas is utilized to cool the motor and the suction gas passes in the vicinity of the vent passage. However, because of the construction of the crankshaft the lubricant in the lubricating system is passed through the aforementioned bearing means to the compression mechanism area to lubricate the bearing means and the compression equipment without the danger of the lubricant passing into the suction gas stream and entering the refrigerant circuit and oil borne refrigerant gas is vented into the suction gas stream without the danger of refrigerant gas starving the aforementioned bearing means of lubrication.

The attached drawing illustrates a preferred embodiment of our invention in which:

FIGURE 1 is a sectional view of a hermetic compressor unit employing the present invention;

FIGURE 2 is an enlarged sectional view of the crankshaft constituting the present invention; and

PlGURE 3 is a cross sectional view of the crankshaft taken along line lll-lil of FIGURE 2.

Referring to FIGURE 1, there is shown the compressor embodying the present invention. This compressor 2 comprises an upper shell and a lower shell 5. These shells are provided with flanged sections 6 and 7 which are intended to meet in sealing contact.v Also included in the compressor is a third shell 8 having a flange 9 which is joined to the flanges 6 and 7 by means of an annular weld By this construction a hermetic housing is formed.

The flan e of the shell g has provided therein suitable openings it to place the upper and lower sections of the The shell 8 also has a lower opening 12. Mounted within the inner shell 8 is a compressor block 15 which consists of a motor flange portion in and a crankcase flange portion 17 divided by a suitable partition 18. Also located in the compressor block are suitable cylinders 19 and Zil. It is appreciated that any desired number of cylinders may be employed. Suitable pistons 21 and 22 are reciprocatingly mounted within the cylinders 19 and 2d and these pistons have mounted therein suitable wrist-pins 23 and 24 which are in turn rotatably connected to the connecting rods 25 and 26. These connecting rods 25 and 26 are rotatably connected to the eccentric portion of the crankshaft 30.

At the extremities of the cylinders 19 and 2d are located suitable valve assemblies 31 and 32 which may be similar to those shown in Patent No. 2,935,248 granted May 3, 1960 to Karl M. Gerteis.

These valve assemblies are retained within their respective positions by suitable spring retainers 33 and 34. These spring retainers 33 and 34 are biased between the valve assemblies 31 and 32 and the shell 8 thereby retaining the valve assemblies in position.

Two circular sealing flanges 37 and 38 are provided on the compressor block in concentric spaced relationship. These particular flanges are provided with suitable. 0

rings 39 and all which seal the space between the block and shell S thereby defining an annular space 41 into which gas compressed within the cylinders 19 and 20 is discharged. The discharge gases are passed from the compressor through the discharge passage 42 which is a short connecting tube extending through the shell 8 and the shell 5. If it is desired, suitable cavities may be incorporated in the annular space 41 to impart a mufiling effect to the discharge gases which are passed from the various cylinders of the compressor. Suction gas is introduced through the opening 63 in the shell 4. This opening 63 permits suction gas to pass into the motor compartment 13 and through the various suction ports 45. The suction ports 45 are connectedto annular spaces 90 located beneath the valve assemblies 31 and 32. A more detailed description of the compression side of the compressor is disclosed in Patent No. 3,008,629 granted November 14, 1961 to Karl M. Gerteis.

It will be noted at this point that the various suction openings 45 are the only openings located in the area of partition 18 with the exception of the bearing housing 46 through which the crankshaft 30 is journaled. This crankshaft 39 comprises a straight portion which is adapted to be connected to the motor 56, a bearing portion 51 which is adapted to be journaled within the bearing housing 46, an eccentric portion 52 adapted to be connected to the various connecting rods which are operatively associated with the pistons, a counterweight section 53 which is adapted to aid in counteracting the unbalance of the eccentric portion 52, pistons 21, 22 and connecting rods 25, 26 and a lower bearing portion 54 which will be described more fully hereinafter.

The motor 56 comprises a stator 57 which is mounted Within the motor flange portion 16 of the compressor block. The stator is inductively connected to the rotor 5S which is force-fitted onto the crankshaft section 50. Located and attached to the rotor 58 is a suitable counterweight 5 which is also adapted to aid in counteracting the running gear unbalance.

In order to direct electric current from a suitable source to the stator 57, a suitable plug 69 is provided in the shell of the compressor in such a manner as to preserve the hermetic nature of the compressor. This plug dtl is connected by suitable conductors 61 to the stator 5'7.

The crankshaft lower bearing portion 54 is journaled within a lower bearing 65 which is mounted in the lower bearing head 64. This lower bearing head 64- is maintained in position by a suitable snap ring 6?; which seats within an annular groove in the compressor block. The bearing head also includes a thrust bearing 66 which has a central opening 67, the function of which will be described more fully hereinafter. Located in the lower portion of the crankshaft adjacent the bearing portion 54- is a concentric hole 68 which constitutes the eye of the impeller of the pump which lubricates the various bearings in the compressor. The eye is a vertically extending hole in communication with the radial hole 69 which extends to the annular space 71. Also located in the shaft is the vertical passage 7% which is in communication with the radial hole 69. Oil which is pumped into the annular space '71 passes through the passage '72 into the filter '73 in which the oil is suitably filtered. The oil that is forced into thevertical passage 70 passes upward to the discharge openings 75 to lubricate the connecting rods and to openings 81 and 82. to lubricate the upper bearings 86 and sfrespectively, the construction of which will be defined more fully hereinafter.

The operation of the compressor is as follows: Suction gas is introduced through the opening 63 and the gas passes over the motor 56 suitably cooling the motor and then passes through the suction inlets &5 through the valve plates 31 and 32 into the cylinders 1g and 2t wherein the gas is compressed. The gas is then, on a discharge stroke, passed into the annular manifold 41 wherein, if desired, a suitable muffler construction may be employed and then passed through the discharge opening 42 out of the compressor.

With respect to the lubrication system of the unit, oil is stored in the sump '76 of the compressor which is the lower portion of the shell 5 and is maintained at an approximate level-shown at 77 in a manner to be described hereinafter. It will be noted that, as a result of the openings ill in the flange section 9 of the shell 8, the motor compartment is vented to the annular space between the shells 5 and 3. Therefore, the lubricant in this space is at suction gas pressure. It will be noted that the crankcase section 14 is isolated from the motor compartment 113 by means of the partition 18 which lies between the motor flange section 16 of the compressor block 15 and the crankcase section 14 of the compressor block. During operation as a result of gaseous refrigerant bypassing the compressor pistons a pressure greater than suction pressure will become evident after a short interval of operation within the crankcase 14. As a result, this gas pressure will substantially force the lubricant in the crankcase 14 out of the crankcase through suitable holes 12' in the lower bearing insert as into the sump and up the annular chamber between the shells 5 and 8. A two-level oil sump results because of the different pressures acting on the oil in the oil sump 76. This is more fully described in Patent No. 3,008,628 granted November 14, 1961 to Karl M. Gerteis et a1.

As the compressor rotates under the influence of the motor as, oil passes through the opening 67 of the thrust bearing 66 into the eye 63 drilled in the lower portion of the crankcase 3%. Since the lower bearing 54 is submerged in oil, the oil in the radial passage 69 as a result of centrifugal force will be cast outwardly, a portion passing into the annular space '71 through the passage '72 through the filter '73 and into the crankcase. This is a standard bypass type filter. The remainder of the oil as a result of the centrifugal force will be urged upwardly above the surface of the oil in the sump through the passage ?tt to the various bearing portions of the compressor.

At this point, it is immediately apparent that two problems arise in the operation of the compressor. Firstly, the crankshaft lubricating passages will after long shutdowns, be filled with refrigerant vapor at levels above the oil sump level indicated at 7'7. At startup after a prolonged shutdown, it will be necessary to remove this refrigerant vapor quickly in order to prevent a vapor lock, which will starve the bearing surfaces and ultimately result in bearing failure. The second problem is that, should uncontrolled venting be permitted, the lubricant passing from the hearing will pass over the outside surface of the bearing housing 46 and ultimately find its way to the various suction openings 45. This flow will be further encouraged by the passage of suction gas over the motor and bearing prior to entrance into the openings 45. The admission of large quantities of oil into the compression equipment will necessarily have an adverse effect upon the valves thereof and furthermore, in normal operation, the passage of quantities of lubricant into'the refrigeration circuit itself will coat the various heat exchange surfaces with an insulating film which will drastically limit the heat exchange qualities of these surfaces.

Referring to FIGURE 2, there is shown a fragmentary sectional view of the crankshaft construction utilized in the present invention. it will be noted that the vertical passage 7ft in crankshaft 51 extends up into the area of bearing housing 45. "By means of two horizontal passages 81 and 82 the oil is directed to the bearings 86 and 37 respectively. Passage 88 vents vertical passage '7ti to the motor compartment 13. A better view of the angular relationship between vertical passage 7 and vent passage $8 is shown in FIGURE 3. As shown in FIGURE 1, rotor as is cut away at 8? to permit venting. I

It will be noted that the crankshaft journaling means comprises two bearing inserts 86 and 37 mounted in the bearing housing 4 5. These inserts are separated from one another by an open space 85. Crankshaft passage 9%) communicates open space with vertical passage '70. A groove 83 in bearing housing 46 permits the lubricant flowing into open space 85 from upper bearing insert 36 to return to crankcase 14.

Upon start-up of the compressor, refrigerant gases lying within the passages 70, 81, 82 and 9t and in open space 85 vent through passage 8% into the motor compartment 23. It is understood that rotation of the previously described pump mechanism causes a build-up of lubricating pressure in passage 70. Since vent passage 88 offers a path of low resistance because of its large cross-sectional area and stra ght through design as opposed to the more restricted clearances of bearings 85, 87 and because of the lower suction pressure in the motor compartment as opposed to the higher crankcase pressure, refrigerant gas in passages 70, 81, 82 and 90, and in open space 85 will vent into the motor compartment.

The lubricating oil, both at start-up and during operation of the compressor, flows to bearings 86, 87 rather than through vent passage 88 into motor compartment 13 or through passage 90 into the open space 85. Vertical passage 70 is offset from the center of rotation of bearing portion 51 of the crankshaft whereby centrifugal force tends to force the liquid-gas mixture in passage 70 outwardly during rotation of the crankshaft. Because of the greater density of the oil, the centrifugal force tends to direct the fiow of pressurized oil into horizontal openings 81, 82 to lubricate bearings 86, 87. It is noted that vent 88 and passage 90 extend in a direction radially opposite to the radial location of passage 70 with respect to the axis of crankshaft bearing portion 51. Further vent 88 has an upwardly rising slope. Accordingly, the oil, in order to pass through vent passage 88 and passage 90 into the motor compartment 13 must overcome centrifugal force acting thereon due to the rotation of the crankshaft bearing portion 51. Additionally, the oil in order to enter the motor compartment 13 must overcome the gravitational force due to the upwardly rising slope of vent passage 88. The pressure of the oil plus the inducing lower pressure in motor compartment 13 is insufiicient to overcome the combined centrifugal and gravitational forces acting on the oil. The oil is accordingly. directed to bearings 86, 87. Oil passed through bearing 86 enters open space 85 and thereafter passes through groove 83 to return to the crankcase 14. Should any oil enter passage 90 during compressor operation, the oil passes into open space 85 for return to the crankcase 14 through groove 83.

Refrigerant gas, because it is of substantially lower density than the oil, is less affected by centrifugal and gravitational forces. Accordingly, during initial operation of the compressor, the refrigerant gas lying within passages 70, 81, 82 and 90, and open space 85 will flow into the motor compartment 13 due to the effect of the lower pressure on, and the relatively non-restricted path of flow offered by, vent passage 88. During operation, any refrigerant gas in the oil will be induced by the lower pressure 'of the motor compartment 13 and the nonrestricted flow path provided by vent passage 88 to enter the motor compartment 13.

As noted refrigerant gas lying in open space 85 is vented into the motor compartment by means of passages 90 and 88. Experience has shown that during short cycling of the compressor little or no refrigerant gas enters open space 85. During long periods of compressor shutdown some refrigerant gas may enter open space 85. Any gas therein readily passes via passages 90 and 88 into the motor compartment 14 upon startup. Should open space 85 be incompletely vented of refrigerant gas at startup, the presence of groove 83 obviates any possibility of vapor lock. Any remaining refrigerant gas is carried by the lubricant into the crankcase via groove 83. As noted, refrigerant gas in the lubricant may be removed during compressor operation via vent 88.

In a construction of the type shown in FIGURE 1 it is important to the successful operation of the compressor that the pressure difference existing between opposite ends of the hearing be maintained, Any uncontrolled venting of the bearing will defeat this aim. By the controlled positive venting construction of the crankshaft of the present invention oil is disinclined to enter the motor compartment.

The present invention provides a crankshaft construction which gives safe and effective venting of refrigerant gas in the crankshaft oil passages. This construction avoids the passage of quantities of oil into the motor compartment where the oil may find its way into the suction openings of the compression equipment and ultimately affect the heat exchange qualities of the various heat exchange members in the refrigeration circuit, yet at the same time effects direct venting of any refrigerant gas in the crankshaft oil passages to the motor compartment thereby avoiding lubrication starvation of the bearings. Furthermore, the possibility of vapor lock occurring on startup and of oil pump noise due to lubricant entrained refrigerant gas is avoided by the positive venting of the various oil passages in the crankshaft.

While we have described a preferred embodiment of our invention, it will be understood that our invention is not limited thereto, since it may be otherwise embodied within the scope of the following claims:

We claim:

1. A reciprocating compressor comprising the combination of a crankcase, cylinder means in said crankcase, piston means reciprocatingly mounted in said cylinder means, a motor compartment above said crankcase, a motor in said motor compartment, partition means separating said motor compartment and said crankcase, upper bearing means in said crankcase above said cylinder means, lower bearing means in said crankcase below said cylinder means, a vertically extending crankshaft journaled in said bearings and operatively connected to said piston means and motor, a lubricating pump adjacent said lower bearing, said upper bearing means comprising first and second spaced bearing members, a vertically extending passage in said crankshaft communicating with said pump, said passage terminating opposite said first bearing member of said upper bearing, a first horizontal passage communicating the terminal end of said vertical passage with said first bearing member, a second horizontal passage communicating said vertical passage with said second bearing member, a connecting passage communicating said space between said first and second bearing members with said terminal portion of said vertical passage, and a vent passage communicating said terminal end of said vertical passage with said motor compartment whereby refrigerant gas in said vertical passage and in said space between said first and second bearing members is vented into said motor compartment.

2. A reciprocating compressor according to claim 1 in which said vertically extending passage is radially offset from said crankshaft axis, said vent passage and said connecting passage extending in a direction opposite from said second horizontal passage, said vent passage having an upwardly rising slope.

References Cited in the file of this patent UNITED STATES PATENTS 2,423,719 Muffly July 8, 1947 2,504,528 Hume Apr. 18, 1950 3,008,629 Gerteis Nov. 14, 1961 3,098,604 Dubberly July 23, 1963 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 162 360 December .22 1964 George T,. Privon et a1 Column 1, line 416 for "comparement" read column 4, line 17, for "crankcase" read crankshaft line 56 for "7" read 7O --O Signed and sealed this 18th day of May 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER A Nesting Officer Commissioner of Patents compartment UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3, 162 360 December 22 1964 George T,. Privon et a1 It is hereby certified that error appears in the ent requiring correction and that the said Letters Patent should read as corrected below.

Column 1 line 46,, for "comparement" read compartment column 4 line 17, for "crankcase" read crankshaft line 56, for "7" read 70 -u Signed and sealed this l8th day of May 1965.

(SEAL) Attest:

ERNEST W. SWIDER A 1 testing Officer EDWARD J. BRENNER Commissioner of Patents 

1. A RECIPROCATING COMPRESSOR COMPRISING THE COMBINATION OF A CRANKCASE, CYLINDER MEANS IN SAID CRANKCASE, PISTON MEANS RECIPROCATINGLY MOUNTED IN SAID CYLINDER MEANS, A MOTOR COMPARTMENT ABOVE SAID CRANKCASE, A MOTOR IN SAID MOTOR COMPARTMENT, PARTITION MEANS SEPARATING SAID MOTOR COMPARTMENT AND SAID CRANKCASE, UPPER BEARING MEANS IN SAID CRANKCASE ABOVE SAID CYLINDER MEANS, LOWER BEARING MEANS IN SAID CRANKCASE BELOW SAID CYLINDER MEANS, A VERTICALLY EXTENDING CRANKSHAFT JOURNALED IN SAID BEARINGS AND OPERATIVELY CONNECTED TO SAID PISTON MEANS AND MOTOR, A LUBRICATING PUMP ADJACENT SAID LOWER BEARING, SAID UPPER BEARING MEANS COMPRISING FIRST AND SECOND SPACED BEARING MEMBERS A VERTICALLY EXTENDING PASSAGE IN SAID CRANKSHAFT COMMUNICATING WITH SAID PUMP, SAID PASSAGE TERMINATING OPPOSITE SAID FIRST BEARING MEMBER OF SAID UPPER BEARING, A FIRST HORIZONTAL PASSAGE COMMUNICATING THE TERMINAL END OF SAID VERTICAL PASSAGE WITH SAID FIRST BEARING MEMBER, A SECOND HORIZONTAL PASSAGE COMMUNICATING SAID VERTICAL PASSAGE WITH SAID SECOND BEARING MEMBER, A CONNECTING PASSAGE COMMUNICATING SAID SPACE BETWEEN SAID FIRST AND SECOND BEARING MEMBERS WITH SAID TERMINAL PORTION OF SAID VERTICAL PASSAGE, AND A VENT PASSAGE COMMUNICATING SAID TERMINAL END OF SAID VERTICAL PASSAGE WITH SAID MOTOR COMPARTMENT WHEREBY REFRIGERANT GAS IN SAID VERTICAL PASSAGE AND IN SAID SPACE BETWEEN SAID FIRST AND SECOND BEARING MEMBERS IS VENTED INTO SAID MOTOR COMPARTMENT. 